Jars & Tins

Canned and jarred goods are foods sealed airtight in tins or glass and heat-processed so that most keep at room temperature, from tinned fish and tomatoes to pickles, jams and soups.

How to choose Jars & Tins

  • High-acid or low-acid. Sour foods such as tomatoes, pickles, fruit and juices keep 12 to 18 months unopened. Meat, poultry, beans, corn and most soups keep two to five years.
  • Packing liquid. Tinned fish comes in oil, water, brine or a sauce. Good packing oil is worth saving for a dressing or a pan of pasta.
  • Dates. Federal rules require a date only on infant formula. A best-by date on a can is about peak quality, so a sound can past it is still safe to open.

About Jars & Tins

Canned and jarred goods last because of two steps: heat and a hermetic, or fully airtight, seal. Commercial canners heat food in its sealed container until it is commercially sterile, which for low-acid foods means about 250°F under pressure.

Acid changes the recipe. The pH scale measures acidity, and lower numbers mean more acid. Foods at 4.6 or below, such as fruit, jams, sauerkraut and pickles, can be processed in boiling water, while red meat, seafood and most vegetables need 240 to 250°F. The method dates back to Nicolas Appert, a French confectioner who collected a government prize for it in 1810.

Keep cans and jars in a cool, dry cupboard that stays below 85°F.

At a glance

Main types
Tinned fish, tomatoes, pickles, jams, soups
Unopened
High-acid 12 to 18 months; low-acid 2 to 5 years
Once opened
Refrigerate; most 3 to 7 days, jams and jellies longer

Jars & Tins questions

Is it safe to eat from a dented can?

A small dent away from the seams is usually fine. Throw out cans that are deeply dented, especially along a seam, and any that are swollen, leaking or heavily rusted. Surface rust you can wipe off is not a problem, but rust inside an opened can is not safe to eat. A bulging or leaking can may signal botulism, so never taste from one to check it.

Are all canned foods safe to store at room temperature?

Most are: commercial canning heats each sealed can or jar until it is commercially sterile, meaning no germs that could grow at normal storage temperatures survive. It stays safe while the seal holds and the can is kept cool. The exceptions say Keep Refrigerated on the label, such as some canned hams and some canned seafood, and they belong in the refrigerator from the day you buy them. Heat over 100°F harms any can.

How long do canned foods keep once they are opened?

Move leftovers into a clean glass or plastic container, cover them and refrigerate. USDA guidance gives opened high-acid foods such as tomatoes, juices and pickles five to seven days, and low-acid foods such as meat, poultry, beans and soup three to four days. The clock starts when the seal is broken, whatever the date on the label.

Sources: USDA Food Safety and Inspection Service; National Center for Home Food Preservation; US Code of Federal Regulations, 21 CFR 113.

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